1. Field of the Invention
This invention relates to circuit board mounting apparatus, and more particularly, to a circuit board mounting apparatus with inverted U-shaped mounting arms for mounting a circuit board.
2. Description of the Prior Art
Many small electronic devices such as telephones, electronic clocks, answering machines, etc., usually use plastic hooks instead of screws for mounting circuit boards inside their plastic housings. Such design can reduce the number of parts used in such small electronic devices and also simplify their assembly processes. FIGS. 1 and 2. shows an example of such plastic hook design used by prior art electronic devices.
FIG. 1 is a perspective view of a circuit board mounting apparatus 2 of a prior art design, and FIG. 2 is a sectional view 1--1 of the circuit board mounting apparatus 2 shown in FIG. 1. FIGS. 1 and 2 show that apparatus 2 comprises a plastic base 4, two front end latching mechanisms 6 installed on the base 4 for horizontally latching the front end 10 of the circuit board 8 in a removable manner, two supporting mechanisms 12 installed on the base 4 which are attached to the bottom side 14 of the circuit board 8 for supporting the circuit board 8 upward, and two rear end latching mechanisms 16 installed on the base 4 for horizontally latching the rear end 18 of the circuit board 8 in a removable manner.
Each of the front end latching mechanisms 6 is a plastic stud which comprises a recess 20 on its upper end. The front end 10 of the circuit board 8 is horizontally and removably engaged in the recesses 20 of the two plastic studs 6. Each of the two supporting mechanisms 12 comprises a positioning stud 22 on its upper end and the circuit board 8 comprises two corresponding positioning holes 24 wherein the two positioning studs 22 are engaged upward in the two positioning holes 24 when the circuit board 8 is mounted on the base 4. The two rear end latching mechanisms 16 are two vertical plastic studs and each of them comprises an inverted L-shaped hook 26 on its upper end for horizontally latching the rear end 18 of the circuit board 8 to prevent it from moving upward. Each of the hooks 26 comprises a slope 28 on its front upper end for allowing the rear end 18 of the circuit board 8 to slide down.
When mounting the circuit board 8 to the base 4, the front end 10 of the circuit board 8 is horizontally inserted into the two recesses 20 of the two front end latching mechanisms 6, and then the rear end 18 of the circuit board 8 is pressed down against the slopes 28 of the two rear end latching mechanisms 16 so that the positioning holes 24 and the rear end 18 of the circuit board 8 can engage with the positioning studs 22 of the two supporting mechanisms 12 and the two hooks 26 of the rear end latching mechanisms 16 separately.
One problem is experienced in using the two rear end latching mechanisms 16. These two vertical studs 16 are usually fairly short in order to keep the circuit board 8 close to the base 4. When removing the rear end 18 of the circuit board 8 from the base 4, the bending force exerted on top of each vertical stud 16 is almost completely transmitted to the connecting part between each stud 16 and the base 4 which frequently breaks the two studs 16. Such problem causes a lot of inconvenience when maintaining a small electronic device which uses such latching mechanism design.